1. Field of the Invention
Embodiments of the present invention relate to a light emitting driver employable by an electroluminescent display and an electroluminescent display including such a light emitting driver. More particularly, embodiments of the invention relate to an electroluminescent display, e.g., an organic electroluminescent display, and a driver thereof that can decrease process/manufacturing cost, decrease process time, and improve manufacturing yield, by implementing a light emitting control driver employing a same transistor type as a pixel circuit of the electroluminescent display.
2. Description of the Related Art
Generally, organic electroluminescent displays are display devices that emit light by electrically exciting fluorescent or phosphorescent materials. Organic electroluminescent displays may drive N×M number of organic electroluminescent display elements to display an image. The organic electroluminescent element may include an anode, e.g., a transparent anode made of, for example, Indium Tin Oxide (ITO), an organic thin film and a cathode, e.g., an opaque cathode made of, for example, a metal. The organic thin film may have a multi-layered structure including an emitting layer (EML) for emitting light by combining electron(s) and hole(s), an electron transport layer (ETL) for transporting the electron(s) and a hole transport layer (HTL) for transporting the hole(s). Further, the organic thin film may include an electron injecting layer (EIL) for injecting the electron(s) and a hole injecting layer (HIL) for injecting the hole(s).
A technique for driving the organic electroluminescent device may include a passive matrix (PM) technique and an active matrix (AM) technique using a thin film transistor (TFT) or a MOSFET. The passive matrix technique may drive a light emitting cell including an anode and a cathode, which overlap each other, e.g., extend orthogonally to each other, by selecting a line. The active matrix driving technique may employ an active device, e.g., a TFT, and a capacitor, and may connect the TFT and the capacitor to respective indium tin oxide (ITO) pixel electrodes in order to maintain a voltage based on a capacitance of the capacitor. The active matrix technique may employ a voltage programming technique or a current programming technique depending on whether a signal applied from a data driver is a current or a voltage.
Organic electroluminescent displays may be used as displays in portable information terminals, e.g., personal computers, handsets, personal digital assistants (PDAs), or various kinds of information machines.
Recently, various kinds of light and small-sized light emitting displays compared to cathode-ray based displays have been developed. Electroluminescent displays, e.g., organic electroluminescent displays, having excellent light emitting efficiency, high luminance, excellent viewing angle, and a high response speed are being researched and developed.
A conventional voltage programming technique for driving, e.g., an organic electroluminescent display may include a light emitting control driver, including both p-type transistors, e.g., PMOS transistors, and n-type transistors, e.g., NMOS transistors.
However, such light emitting control driving circuits including both PMOS and NMOS transistors, include a separate external driver and, fabrication thereof, include additional processing steps to accommodate both the n-type and p-type transistors. Therefore, the resulting organic electroluminescent display may be relatively large in size, relatively heavy, and manufacturing thereof may involve more complicated and/or lengthy processing.